Unitary removal of plaque

ABSTRACT

Novel apparatus and related methods are disclosed by which plaque is connected to the head of a removal instrument for removal of a unitary segment of plaque from an artery intact to increase blood flow through the artery.

This application is a continuation-in-part of U.S. patent applicationSer. No. 07/973,514, filed Nov. 9, 1992, now abandoned.

FIELD OF INVENTION

The present invention relates generally to increasing blood flow inarteries and, more particularly, to unitary removal of a segment ofplaque from an artery.

BACKGROUND

Constricted blood flow in human arteries due to build-up of plaque is acommon ailment and creates serious risks to the quality of life and, insome cases, e.g., when build-up occurs in coronary arteries, to lifeitself, too frequently at an early age.

Past efforts to address the problem of plaque accumulation in arterieshave consisted primarily of conventional endarterectomy, by-passsurgery, dilation of the afflicted arteries using dottering or balloonangioplasty (PTA and PTCA), atherectomy, and successive severing of thinlayers of plaque by reason of repeated passes of a cutting or grindinginstrument along the plaque region where removal is desired. Theplaque-cutting technique also requires that debris, in the form ofplaque fragments released into the blood stream, be collected andremoved from the artery to avoid complications (such as embolization andthrombosis). Laser removal of plaque is also known.

Conventional endarterectomy is invasive. By-pass surgery is traumatic tothe tissue, very expensive, very invasive, and creates the greatest riskto the patient. Balloon angioplasty and/or dottering are often only atemporary or short-term solution, as all of the plaque in the afflictedartery at the time of treatment remains there. Dilation only rearrangesplaque and may cause pieces of plaque to break loose into the bloodstream. Additional build-up of plaque at the site of treatment can beprevented or alleviated by exercise and diet control, if patientcompliance can be achieved. Atherectomy has demonstrated poor long-termresults, at least in peripheral vessels.

Repeated cutting of the atheroma using a reciprocated instrument offerspromise, but cannot be performed rapidly, may not remove all of theplaque at the treatment site, and risks complications when and if plaquefragments are not collected and thus escape to flow with blood to otherparts of the cardiovascular system. Laser removal of plaque has alsoshown poor long-term results in some studies.

All present treatments exhibit restenosis, a complex, poorly understoodprocess by which the artery becomes re-blocked by material that includesuncontrolled growth of smooth muscle cells (intimal hyperplasia ormyointimal fibroplasia). All present treatments vary in peri-operativemeasures of desirability, including duration of procedure, degree ofinvasiveness of procedure, number and size/length of surgical incisionsrequired, length of stay in hospital, recuperation/healing time, timeuntil return to work, degree of anesthesia (local/general) required,overall procedure risk, and overall treatment cost.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION

In brief summary, the present invention overcomes or alleviates problemsof the prior art. It is believed that a less traumatic, lower risk, lessexpensive, less invasive, less time-consuming, and more efficaciousplaque treatment apparatus and related methods are provided by which aunitary segment of plaque is removed intact from an artery.

With the foregoing in mind, it is a primary object to overcome oralleviate problems of the prior art.

A further object of paramount importance is the provision of novelplaque treatment apparatus and related methods.

Another object of value is the provision of apparatus and methodology bywhich a unitary segment of plaque is removed intact from an artery.

An additional object of importance is the provision of what is believedto be a significantly less traumatic, lower risk, less expensive, lessinvasive, less time-consuming, and more efficacious way of treatingplaque.

A further object of significance is the provision of a novel plaqueremoval apparatus and method having one or more of the followingfeatures: (1) applicable for plaque removal in arteries of all sizesincluding all peripheral, coronary, and carotid arteries, (2) which canuse one or two relatively small incisions, (3) which is effective withor without pre-loosening of plaque; (4) which is operable with orwithout a guidewire; (5) which can be placed in the artery of choiceeither concentrically or eccentrically; (6) usable alone or incombination without other plaque treating procedures; (7) usable in bothpartially and totally occluded arteries; and (8) useable in either anopen surgical procedure or a percutaneous procedure.

These and other objects and features of the present invention will beapparent from the detailed description taken with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary longitudinal cross-section of aplaque-connecting instrument, in diametrally-constricted orientation,disposed in a plaque-ladened artery.

FIG. 2 is a fragmentary longitudinal cross-section illustrating theinstrument being pulled while in a radially-expanded, plaque-connectingposition;

FIG. 3 is a transverse cross-section taken along lines 3--3 of FIG. 2;

FIG. 4 is a fragmentary longitudinal cross-section of a secondplaque-connecting instrument, in a diametrally-constricted orientation,disposed in a plaque-ladened artery.

FIG. 5 is a fragmentary longitudinal cross-section illustrating theinstrument being pulled while in a radially-expanded plaque-connectingposition;

FIG. 6 is a transverse cross-section taken along lines 6--6 of FIG. 5;

FIG. 7 is a fragmentary longitudinal cross-section of aplaque-connecting instrument, being pulled while in a hooked positionwith plaque in an artery;

FIG. 8 is a fragmentary longitudinal cross-section similar to FIG. 7showing a segment of plaque being displaced with the connectinginstrument along the length of the artery;

FIG. 9 is a transverse cross-section taken along lines 9--9 of FIG. 8;

FIG. 10 is an elevational view of a segment of plaque removed intactfrom an artery using the present invention;

FIG. 11 is a flow chart depicting various ways of implementing thepresent invention; and

FIG. 12 is a fragmentary longitudinal cross-section of theplaque-connecting instrument eccentrically or asymmetrically insertedinto an artery, i.e., between the inner arterial wall and the plaque.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference is now made to the drawings wherein like numerals are used todesignate like parts throughout. The present invention provides forunitary, intact removal of a segment of plaque from an artery, toresolve or alleviate constrictive blood flow problems in human arteries.The invention overcomes or alleviates health risks associated withconventional endarterectomy, by-pass surgery, dottering and balloonangioplasty procedures, atherectomy, reciprocal cutting of layers ofplaque, and laser plaque removal. It is believed that intact removal ofone or more segments of plaque, in accordance with the principles of thepresent invention, is less traumatic, creates lower risks, is lessexpensive, is less invasive, less time-consuming, and is moreefficacious than by-pass surgery, angioplasty, and reciprocal cutting ofplaque.

Reference is now made to FIG. 11, for the purpose of providing adescription of the present invention which is comprehensive. Initially,at least one man-made opening and in some cases only one opening iscreated in the artery, at a readily accessible site, for which plaquetreatment is desired. This can be done conventionally, by making a smallsurgical incision in the artery of no greater size than needed or bymaking a small puncture in the vessel, such as a percutaneous puncture,followed by conventional insertion of a guidewire, which may or may notbe followed by sheath insertion including insertion of a sheathparticularly suitable to plaque removal.

As a preliminary to intact removal of a unitary segment of plaque, oneor more plaque-loosening techniques may be employed, at the discretionof the health care provider. For example, where one incision or otherman-made opening is used, the plaque adjacent thereto may be generallyradially and/or circumferentially cut or bluntly dissected so as to makeremoval easier, sure, and predictable. Where two incisions or otherman-made openings are made in the length of artery to be treated, theplaque, at both man-made openings, may be generally radially and/orcircumferentially cut or bluntly dissected for ease and predictabilityof plaque segment removal.

If desired, a dottering instrument may be inserted and caused to vibrateand/or rotate so as to impact in a sequential fashion upon plaqueadhering to the interior wall surface of the length of artery to betreated. The dottering instruments disclosed in pending U.S. Trademarkapplication Ser. No. 07/943,514, filed Nov. 9, 1992, now abandoned(owned by the assignee of the present invention), may be utilized to sopreliminarily loosen the plaque to be later unitarily removed from theartery. A second purpose for use of a dottering instrument is to enlargethe lumen or pathway to permit insertion of the plaque-connectinginstrument.

Thereafter, a suitable instrument is placed, inserted, or introducedthrough the man-made opening into the artery, for example, although notnecessarily, along an indwelling guidewire. The insertion can begenerally concentric within the plaque-ridden lumen of the artery (seeFIG. 1, for example) or eccentric, i.e., between the arterial wall andthe plaque (see FIG. 12, for example).

After instrument insertion, instrument displacement continues, byexercise of external control, until the head of the instrument has beendisplaced to and located at a desired site adjacent to plaque within theartery, normally removed or remote from the insertion site. A suitableexternal control, which may be used in practicing the principles of thepresent invention, is disclosed in co-pending U.S. patent applicationSer. No. 07/973,514, filed Nov. 9, 1992 (owned by the assignee of thepresent invention), and abandoned.

When so disposed, positioned, or placed, the head of the instrument isconnected, on a temporary or releasible basis, to the adjacent plaquewhereby the instrument is tethered to the plaque. The connection may beby grabbing, gripping, compressively holding, clamping, and/or embeddingplaque within the head so as to bind together the plaque and the head,grasping, and/or holding the plaque by or at the head. The connectionmay or may not also simultaneously create a tapering interface betweenthe engaged plaque and neighboring plaque that has not been engaged.

Once the releasible connection has been created between the head of theinstrument and the adjacent plaque, the instrument is displaced so as toapply force to the tethered plaque, i.e., the plaque to which thereleasible connection has been made. While the primarily force is one ofpulling or stretching the plaque along the length of the artery in adirection generally parallel to the longitudinal axis of the artery andopposite to the direction of insertion, other motions may also be used.For example, the releasible connection internally within the artery maybe achieved using at least some rotation and, thereafter, additionalrotation may be applied in one or both directions to assist inseparating a length of plaque from its adhered relation within theartery. Similarly, the head may be advanced and retracted to the sameend. In some applications including two-incision situations, the plaquemay be engaged and then pushed toward the second incision, rather thanbeing pulled back toward the first incision. The direction of theinsertion and force applied is independent of the arterial flowdirection, i.e., it may be either antegrade or retrograde to normalblood flow.

The above-mentioned instrument displacement while the head is releasiblyconnected to the plaque results in tearing, severing, shearing,separating, and/or peeling instantly or progressively of a segment ofplaque as a unit from the artery. The plaque segment can be separatedfrom residual arterial plaque, including adjacent plaque by tearing orshearing or by radially and/or circumferentially cutting using asuitable instrument. Plaque may also separate along a created taperinginterface due to the force transmitted through the connecting plaque asit is manipulated by the connecting instrument.

One principle at work here is that a chain is as strong as its weakestlink. The force transmitted to the plaque eventually produces separationat the plane between tissue layers where the connection between thelayers is weakest. In practice, this weakest connection generally occursat the plane between the diseased tissue and the non-diseased tissue.The weakness at this plane is related to the weakness exploited usingblunt dissection in conventional endarterectomy, although the physicalmechanism described herein exploits this weakness in quite a differentway which in no way employs the blunt dissection used in conventionalendarterectomy.

The severed unitary segment of plaque is, finally, retrieved, withdrawn,and removed from the artery through the insertion site along with theinstrument head to which the plaque segment is temporarily connected, orthrough another site toward which the head has pulled or pushed theplaque.

While the health care provider can, thereafter, insert a synthetic orbiologically-obtained lining into the treated artery, the presentinvention comprehends as well terminating the procedure upon withdrawalof the plaque segment and removal head, followed by suitable closing ofthe one or more man-made openings in the artery.

The present invention comprehends provision of an apparatus for excisinga segment of plaque intact from the artery which comprises an instrumentequipped with a plaque-engaging head comprising a connector by which thehead is temporarily joined to plaque within the artery and by whichforce is applied to the plaque to loosen and remove a continuous segmentthereof. The instrument comprises a mechanism including an externalcontrol by which the instrument, its head, including its connector, aremanipulated to locate the head adjacent the plaque to be engaged, whichis normally remote from the insertion site, for temporarily orreleasibly connecting the connector to the plaque without severing orfragmenting the plaque, for applying a force across the connector to theconnected plaque sufficient to sever the segment of plaque intact fromthe artery and for removing the severed segment of plaque from theartery. A typical length of plaque so removed from an artery isillustrated in FIG. 10. The plaque segment can be short or it can bevery long, for example 15-18 inches. It is, however, to be appreciatedthat the present invention is not restricted to any particular type ofinstrument. Any instrument capable of being connected to arterial plaqueat a desired site and by which the connected plaque can be unitarilyremoved intact as a segment from the artery may be used. The form ofreleasible connection may be binding, snagging, compressively holding,taking hold of, grasping, grabbing, hooking, piercing, rotationalengagement, clamping, biting, embedding, or in any other suitable way.

Notwithstanding the foregoing, FIGS. 1-3, 4-6, and 7-9 illustratedifferent mechanical configurations by which an instrument head istemporarily connected to plaque for purposes of unitary removal intactof a plaque segment. With specific reference to FIGS. 1-3, aninstrument, generally designated 20, is there illustrated as having beeninserted through a man-made opening in an artery, generally designated22, in a generally concentric fashion so as to be disposed generallycentrally within a lumen 24 of the artery constricted by asurface-irregular deposit of plaque 26. Insertion is illustrated asbeing achieved conventionally along an indwelling guidewire 28 in acollapsed or diametrically-small configuration. The instrument comprisesa first relatively large tube 30 through which a smaller tube 32generally concentrically passes. The instrument 20 comprises a head,generally designated 34 comprising a plurality of plaque connectors,each designated 36, in the form of resilient, helically-disposed blades.Each blade 36 is illustrated as being centrally enlarged at 37. Theblades are joined at their respective proximal ends to the proximalportion 38 and to a distal tip 40 at their respective distal ends andmay or may not pivot at their ends relative to proximal portion 38 anddistal tip 40. The tube 32 extends centrally between the blades 36 andis securely non-rotatably fastened to the proximal portion of the distaltip 40.

Once the head 34, in its constricted position, is disposed at a desiredlocation along the artery 22 adjacent a desired portion of plaque 26, anexterior control, such as the one disclosed in pending U.S. patentapplication Ser. No 07/973,514, filed Nov. 9, 1992, now abandoned isused to longitudinally retract tube 32 and tip 40 in respect to tube 30causing the plaque-connector blades 36 to flex from the constrictedposition of FIG. 1 to the radially expanded position of FIG. 2.

Thereafter or simultaneously therewith, the head 34 is pulled and/orrotated so as to create a releasible or temporary connection between thehead 34 and the plaque engaged by the blades 36, as shown in FIG. 3.This grasping, grabbing, clamping, binding or like phenomenon causes theconnected plaque to move as the instrument head 34 is moved bymanipulation of the external control. Thus, the head 34 can be movedback and forth and/or can be rotated in one or the other or bothdirections so as to radially and/or circumferentially sever or shear theplaque from itself, as illustrated at site 42 in FIG. 2. The instrument20 and its head 34 are retracted in a generally longitudinal or axialdirection, either alone or in conjunction with back/and forth movementas well as selected rotational movement in one or the other, or bothdirections. This causes the plaque to be sheared, peeled, or be severedfrom the internal surface 44 of the internal wall 46 of the artery 22,which defines the boundary between the arterial wall and the engagedplaque. It is to be appreciated that as arterial disease progresses,this boundary between the diseased and undiseased arterial wall may belocated within the interior layer 46, or between layers 46 and 52, orwithin layer 52, but does not generally invade layer 50. The severedunitary plaque segment 26' is retrieved together with the connected head34 and removed through the man-made opening in the artery and whenremoved and disconnected from the head has a worm-like appearance asshown in FIG. 10. Plaque segment 26' might be called an endarterectomyplug. Medically speaking, it is by definition an endarterectomy plug,although the endarterectomy has been achieved by novel, non-conventionaltechniques.

In medical terms, the artery 22 comprises an outside layer 50 known asthe tunica adventitia, a central, radially larger intermediate layer 52,known as the tunica media, and the previously mentioned interior layeror wall 46, known as the tunica intima endothelium. The plaque 26 istypically referred to as atherosclerotic plaque, which in advancedstages of disease such as are typically treated, partially or wholly,engulfs the tunica media.

The present invention, as stated earlier, does not contemplate cutting,grinding, or fragmenting pieces of plaque 26 from the atheroma, butrather is directed to grasping, gripping, clamping, or otherwisereleasibly connecting the instrument head to the plaque for intactremoval of a segment of plaque and in certain embodiments, including theembodiments disclosed herein, contemplates simultaneously creating atapered interface. The creation of the tapered interface is advantageousin that, after the treatment when flow is restored, a tapered interfacein the upstream direction will help prevent the creation of undesirableflaps of disease being lifted from the vessel wall, as the flow over thetapered disease will press the disease more firmly into the vessel wall,and also reduce flow turbulence at the interface.

Reference is now made to the instrument illustrated in FIGS. 4-6, whichis generally designated 20'. The instrument 20' is connected andcontrolled as is the above-described instrument 20. Only differencesbetween instrument 20 and instrument 20' need description here. Thenumerals used in FIGS. 4-6 which are identical to numerals used in FIGS.1-3 identify identical or substantially identical parts. The instrument20' differs from the instrument 20 primarily in the configuration ofconnector head 34'. Head 34' comprises a plurality of spaced, somewhatlongitudinally-extending blades 36' anchored, respectively, at theproximal ends 38 thereof to the distal portion of the tube 30 andnon-rotatably joined to the tip 40. Each blade 36' comprises aproximally-directed barb 37'. While each barb 37' is illustrated asbeing disposed at a slight acute angle in respect to the longitudinalaxis of the artery 22, any suitable barb orientation may be used.

When the tube 32 is retracted by the external control in respect to tube30, tip 40 is displaced toward proximal portion 38, causing the blades36' of the head or connector 34' to flex radially outwardly. Withdrawal(retraction) and/or rotation of the head 34' causes the blades 36' tobite into, but not sever away pieces of the plaque 26. Generallylongitudinal retraction of the instrument 20', including connecting head34' with the plaque 26 bindingly connected between the blades 36',accommodates severing or shearing of the plaque at radially-directedsite 42 thereby separating plaque segment 26' from residual arterialplaque 26. This severing or shearing can create a tapered or beveledinterface. The retraction of the instrument 20' may be accompanied by toand fro longitudinal movement of the head 34', retraction only and/orrotation in one or the other or both directions sufficient to sever,shear, or peel the plaque segment 26' from the annular interface 44 ofthe inner layer 46 of the artery 22, or at whatever depth thediseased/non-diseased interface has progressed, as described earlier.

The severed plaque segment 26' is retrieved and removed from the arterythrough a man-made opening therein as the instrument 20' is removed, thehead 34' remaining releasibly connected to the plaque segment 26' duringretrieval and removal.

Reference is now made to the unitary plaque segment removal instrument,generally designated 20", illustrated in FIGS. 7-9. To the extent partsof instrument 20" illustrated in FIGS. 7-9 are identical orsubstantially identical to parts previously described in connection withFIGS. 1-3, identical numerals are used and no further descriptionthereof is necessary.

Tube 30 and distal portion 38 thereof do not form a part of theembodiment illustrated in FIGS. 7-9. Instrument head 34" isnon-rotatably secured at the distal end of tube 32 and is inserted intothe desired location along guidewire 28. The instrument head 34" isillustrated as maintaining a constant transverse dimensionalconfiguration.

Head 34" comprises a plurality of curvilinear blades 36", each of whichis illustrated as carrying a pair of curved hooks 39, which engage theplaque when rotated so as to pierce portions thereof without severingpieces of plaque therefrom. Thereafter, by displacing the head 34" toand fro, or by retracting alone and/or rotationally as desired and byprimarily retracting the head 34" along the length of the artery 22,plaque segment 26' is loosened, severed, retrieved, and removed from theartery through a man-made opening therein.

Reference is now made to FIG. 12, which illustrates the same apparatusas shown in FIGS. 1-3, illustrating placement of the instrument head 34into the artery between the plaque 26 and the arterial wall surface orcleavage interface of weakness 44 and advanced along the arterialsurface 44 to the desired plaque connection site without prior use of aninterface separation tool.

The invention may be embodied in other specific forms without departingfrom the spirit of essential characteristics thereof. The presentembodiments therefore to be considered in all respects as illustrativeand are not restrictive, the scope of the invention being indicated bythe appended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:
 1. Amethod of excising plaque from an artery comprising the stepsof:inserting an instrument into the artery, the artery having an axis;placing the instrument adjacent to plaque in the artery; grasping theplaque with the instrument without materially cutting the plaque by theinstrument; maintaining grasp while displacing the instrument along theaxis of the artery thereby generally axially dislodging a length ofplaque from the artery; removing the dislodged length of plaque from theartery.
 2. A method of removing arterial plaque comprising the stepsof:grabbing hold of plaque within an artery with a removal instrument;applying force to the plaque generally along the length of the artery tosever without longitudinally cutting a segment of plaque from a portionof a wall of the artery; withdrawing the plaque segment from the artery.3. A method of increasing blood flow in an artery comprising the stepsof:introducing a gripping instrument into an artery through a man-madeopening therein; displacing the gripping instrument along the artery toa site where the artery is obstructed at least in part by plaque;gripping plaque at the site with the gripping instrument; tearing plaquefrom the artery without cutting the plaque along the axis of the arteryby displacing the instrument while the instrument is gripping theplaque; removing the instrument and the gripped plaque through theman-made opening.
 4. A method of increasing blood flow in an arterycomprising the steps of:tethering arterial plaque to an indwellinginstrument at a site within the artery with immaterial axial cutting oftethered plaque, pulling the instrument and plaque along the length ofthe artery thereby forcibly tearing a segment of plaque, in thedirection of the length of the artery, from a portion of the artery andremoving the torn plaque segment from the artery.
 5. A method oftreating plaque in an artery having an elongated length to increaseblood flow comprising the steps of:inserting a connecting head into anartery; locating the head adjacent to plaque within the artery;removably connecting the head to the plaque without cutting plaque fromthe artery along its length; pulling on the plaque through the headthereby severing a segment of plaque intact from the artery; retrievingthe head and connected severed segment of plaque from the artery.
 6. Amethod according to claim 5 wherein the inserting step is preceded bycreating at least one man-made opening in the artery.
 7. A methodaccording to claim 6 wherein the inserting step comprises placing aguidewire through the opening and advancing the head into the arteryalong the guidewire.
 8. A method according to claim 5 wherein theinserting step is preceded by preliminarily loosening the plaque.
 9. Amethod according to claim 8 wherein the loosening step comprises makingat least one radial cut in the plaque.
 10. A method according to claim 5wherein the locating step comprises placing the head within a centrallumen of the artery.
 11. A method according to claim 5 wherein theremovably connecting step comprises taking hold of the plaque by thehead.
 12. A method according to claim 5 wherein the removably connectingstep comprises grasping the plaque by the head.
 13. A method accordingto claim 5 wherein the removably connecting step comprises grabbing theplaque by the head.
 14. A method according to claim 5 wherein theremovably connecting step comprises engaging the plaque by the head. 15.A method according to claim 5 wherein the severing step comprisesshearing the plaque intact from a wall of the artery.
 16. A methodaccording to claim 5 wherein the retrieving step comprises removing thehead and the severed segment of plaque from the artery.
 17. A methodaccording to claim 5 wherein the removably connecting step compriseshooking the plaque with the head.
 18. A method according to claim 5wherein the removably connecting step comprises piercing the plaque withthe head.
 19. A method according to claim 5 wherein the removablyconnecting step occurs due to rotating the head.
 20. A method accordingto claim 19 wherein the rotating step comprises causing the head tobindingly bite into the plaque.
 21. A method according to claim 19wherein the rotating step comprises embedding plaque within the head inbinding relation.
 22. A method according to claim 5 wherein theremovably connecting step comprises binding the plaque and the headtogether.
 23. A method according to claim 5 wherein the removablyconnecting step comprises snagging the plaque with the head.
 24. Amethod according to claim 5 wherein the locating step comprisesadvancing the head to an arterial location remote from the insertionsite.
 25. A method of treating plaque in an artery to increase bloodflow comprising the steps of:preliminarily loosening the arterial plaqueby subjecting the plaque to be removed to dottering; inserting aconnecting head into an artery; locating the head adjacent to plaquewithin the artery; removably connecting the head to the plaque; pullingon the plaque through the head thereby severing a segment of plaqueintact from the artery; retrieving the head and connected severedsegment of plaque from the artery.
 26. A method of treating plaque in anartery to increase blood flow comprising the steps of:preliminarilydisplacing the plaque by subjecting the plaque to be removed to balloonangioplasty; inserting a connecting head into an artery; locating thehead adjacent to plaque within the artery; removably connecting the headto the plaque; pulling on the plaque through the head thereby severing asegment of plaque intact from the artery; retrieving the head andconnected severed segment of plaque from the artery.
 27. A method oftreating plaque in an artery to increase blood flow comprising the stepsof:inserting a connecting head into an artery; locating the headadjacent to plaque within the artery by placing the head within theartery between the plaque and a wall of the artery so that insertion ofthe head separates in part the plaque and the artery at the interfacebetween the two; removably connecting the head to the plaque; pulling onthe plaque through the head thereby severing a segment of plaque intactfrom the artery; retrieving the head and connected severed segment ofplaque from the artery.
 28. A method of treating plaque in an artery toincrease blood flow comprising the steps of:inserting a connecting headinto an artery; locating the head adjacent to plaque within the artery;removably connecting the head to the plaque by compressively holding theengaged plaque at the head; pulling on the plaque through the headthereby severing a segment of plaque intact from the artery; retrievingthe head and connected severed segment of plaque from the artery.
 29. Amethod of treating plaque in an artery to increase blood flow comprisingthe steps of:inserting a connecting head into an artery; locating thehead adjacent to plaque within the artery; removably connecting the headto the plaque; pulling on the plaque through the head by stretching theplaque thereby severing a segment of plaque intact from the artery;retrieving the head and connected severed segment of plaque from theartery.
 30. A method of treating plaque in an artery to increase bloodflow comprising the steps of:inserting a connecting head into an artery;locating the head adjacent to plaque within the artery; removablyconnecting the head to the plaque; pulling on the plaque through thehead thereby severing a segment of plaque intact from the artery byprogressively peeling the plaque intact from a wall of the artery;retrieving the head and connected severed segment of plaque from theartery.
 31. A method of treating plaque in an artery to increase bloodflow comprising the steps of:inserting a connecting head into an artery;locating the head adjacent to plaque within the artery; removablyconnecting the head to the plaque; pulling on the plaque through thehead thereby severing a segment of plaque intact from the artery by bothseparating the plaque segment from other plaque within the artery andseparating the plaque segment from a wall of the artery; retrieving thehead and connected severed segment of plaque from the artery.
 32. Amethod of treating plaque in an artery to increase blood flow comprisingthe steps of:inserting a connecting head into an artery; locating thehead adjacent to plaque within the artery; removably connecting the headto the plaque by clamping the head to the plaque; pulling on the plaquethrough the head thereby severing a segment of plaque intact from theartery; retrieving the head and connected severed segment of plaque fromthe artery.